Human paraventricular nucleus (PVN) in this coronal section is indicated by the shaded area. Dots represent vasopressin (AVP) neurons (also seen in the supraoptic nucleus, SON). The medial surface is the 3rd ventricle (3V), with more lateral to the left.

Magnocellular neurons of the PVN and SON project to the posterior "lobe" of the pituitary

The parvocellular neurosecretory neurons of the PVN project axons to the median eminence, at the base of the brain. At the median eminence, the neurosecretory nerve terminals release peptides into the blood vessels of the hypothalamo-pituitary portal system. These vessels carry the peptides to the anterior pituitary gland, where they regulate hormone secretion into the systemic circulation. The parvocellular neurosecretory cells include cells which make the following hormones:

As well as neuroendocrine neurons, the PVN contains interneurons and populations of neurons that project centrally (i.e. to other brain regions). The centrally-projecting neurons include:

parvocellular oxytocin cells that project mainly to the brainstem and spinal cord. The oxytocin cells that project to the brainstem are involved in gastric reflexes, those that project to the spinal cord are involved in penile erection.

parvocellular vasopressin cells that project to many areas of the hypothalamus and limbic system, as well as to the brainstem and spinal cord. These neurons are involved in blood pressure regulation and thermoregulation.

parvocellular CRH neurons that are thought to be involved in stress-associated behaviors

Amongst these, inputs from neurons in structures adjacent to the anterior wall of the third ventricle ("AV3V region") carry information about the electrolyte composition of the blood, and about circulating concentrations of hormones such as angiotensin and relaxin to regulate the magnocellular neurons.